1. FIELD OF THE INVENTION
This invention relates to a novel chemical dispenser for dispensing a predetermined volume of chemical solution into a body of water such as the water in a toilet tank. More particularly, it relates to a dispenser wherein the chemical solution contained in the dispenser is effectively isolated from the body of water during the periods of quiescence.
2. DESCRIPTION OF THE PRIOR ART
There are many types of dispensers for releasing various chemicals such as detergents, disinfectants, etc. into toilet tanks. Depending upon the chemical being utilized there is a need for the dispenser to release the chemical at varying rates. For example, a disinfectant solution to be effective should be released into the tank during the latter portion of the flushing cycle so that the solution is not flushed away. It is desirable in each of these dispensers to provide a means for isolating the chemical solution from the tank during quiescent periods. This prevents unnecessary and wasteful leakage of chemicals into the tank. Dispensers for achieving such a isolation of chemicals are generally categorized as passive or active.
Passive dispensers achieve their purpose without moving parts by proper dimensioning of the ports and internal passages of the dispenser. For example, U.S. Pat. No. 4,208,747 (Dirksing), describes a chemical solution dosing dispenser for dispensing the solution into a toilet tank when the toilet is flushed. This device employs a trapped air bubble in the siphon tube to provide an air lock which, in the quiescent period between flushes, isolates the solution in the dispenser from the water in the tank. To form the air bubble Dirksing forms the upper end of his siphon tube into a hook that has a constricted diameter and which forms a pocket in which air can collect during the filling cycle when water from the toilet tank is entering the dispenser.
A disadvantage of the Dirksing device is, however, its manufacture is complicated by the fact that the operation of the device is highly dependent upon its relative internal dimensions.
Active dispensers achieve their isolating function with some type of moving component such as a valve. The valve is designed to open or close at various times in the flushing cycle in order to release the proper amount of chemical solution only during desired portions of the cycle. Active dispensers are necessarily more complex than passive dispensers and are subject to consumer misuse. Such dispensers are also more difficult to produce since manufacturing tolerances of the various parts are more critical than other dispensers and since they require more parts and assembly operations.
One example of an active dispenser is shown in U.S. Pat. No. 3,778,849 (Foley). The Foley device utilizes two valves in conjunction with ports and tubes having predetermined dimensions. The valves open and close in response to varying pressures which change as a function of the water level within the toilet tank.
A passive means for forming an isolating air lock is disclosed in a co-pending application assigned to the same assignee. The porous member used in that device, however, restricts the discharge rate into the tank which, in some situations, may be undesirable.
It is an object of this invention to produce a toilet tank dispenser which can control the rate at which a chemical solution is dispensed and which utilizes an active means to create an air lock. It is a further object of this invention to produce such a dispenser where the air lock forming means does not restrict the discharge rate of the dispenser.